Cytokines Accumulated in Acquired Renal Cysts in Long-Term Hemodialysis Patients

<i>Background:</i> Cytokines play a pivotal role in growth, differentiation, and apoptosis. In this study, we measured cytokine content in the renal cyst fluid of patients with acquired cystic disease of the kidney (ACDK) in order to elucidate the possibility that cytokines are related to the development of ACDK. <i>Patients and Methods:</i> All or some of 15 cytokines, IL-1a, -1b, -2, -4, -5, -6, -8, -10, IFN-α, -γ, G-, M-, GM-CSF, TNF-α, and vascular endothelial growth factor (VEGF) were analyzed in cyst fluid and serum of 12 patients on hemodialysis (HD) including 8 with ACDK and 8 with normally functioning kidneys by sandwich enzyme-linked immunosorbent assay. <i>Results:</i> Out of these cytokines, only IL-6, -8, M-CSF, and VEGF were detected in the cyst fluid of patients with ACDK. Moreover, IL-6, -8, and VEGF showed significantly higher concentrations in the cyst fluid than in the blood (194.9 ± 90.9 vs. 0.0 ± 0.0 pg/ml, 2,377.5 ± 602.9 vs. 0.0 ± 0.0 pg/ml, 5,167.8 ± 1,316.9 vs. 41.1 ± 14.7 pg/ml, respectively), while M-CSF showed comparable concentrations in the cyst fluid with those in the blood (3,519.4 ± 730.0 vs. 3,250.3 ± 319.1 pg/ml, p = 0.69). Additionally, IL-6, -8, and VEGF accumulated more abundantly in the cyst fluid of patients with ACDK than in that of patients with other cystic nephropathies including ADPKD patients on HD (194.9 ± 90.0 vs. 4.6 ± 3.2 pg/ml, 2,377.5 ± 602.9 vs. 76.8 ± 46.5 pg/ml, 5,167.8 ± 1,316.9 vs. 131.1 ± 63.1 pg/ml, respectively). However, there was no significant correlation between the intracystic concentrations of these cytokines and the corresponding cyst diameters. <i>Conclusion:</i> These results showed that in ACDK patients a local environment exists in which production or accumulation of certain cytokines is selectively enhanced compared with patients with other cystic nephropathies. They imply that these cytokines are closely related to pathogenesis particular to ACDK.